A comparative study of two polymorphs ofL-aspartic acid hydrochloride

Abstract

Two polymorphs of L-aspartic acid hydrochloride, C4H8NO4(+)·Cl(-), were obtained from the same aqueous solution. Their crystal structures have been determined from single-crystal data collected at 100 K. The crystal structures revealed three- and two-dimensional hydrogen-bonding networks for the triclinic and orthorhombic polymorphs, respectively. The cations and anions are connected to one another via N-H···Cl and O-H···Cl interactions and form alternating cation-anion layer-like structures. The two polymorphs share common structural features; however, the conformations of the L-aspartate cations and the crystal packings are different. Furthermore, the molecular packing of the orthorhombic polymorph contains more interesting interactions which seems to be a favourable factor for more efficient charge transfer within the crystal.

Intermolecular interactions and chiral crystallization effects in (1,5,3-dithiazepan-3-yl)-alkanoic acids

“…Such examples involve cocrystals with water molecules, chloride ions (code MUCKUR02 (ref. 37)), nitrate ions (code HUMLIK 38 ), sulphate ions (code NELQUQ 39 ), acetate ions (code MUVXAC 40 ) etc. In our case, compound 2 with an achiral glycine fragment does not crystallize also in its own phase and thereby forms cocrystals with water (2a) and dimethyl sulfoxide (2b) molecules.…”

Crystal engineering of a new pharmaceutical polymorph of gallic acid monohydrate: a structural comparative study and chemical computational quantum investigations

“…During the last few years, we have succeeded in synthesizing new polymorphs by acting on crystallization conditions. 31,32 In this paper, GA is used because of its richness in hydrogen bonds and the several possibilities of hydroxyl group orientation. It is also unique in the diversity shown by exhibiting polymorphism in its hydrated or anhydrous forms.…”